SALT LAKE CITY (AP) — A federal employee who managed operations at the building bombed in Oklahoma City in 1995 is set to testify Thursday about surveillance cameras as the FBI attempts to show there are no unreleased videos of the attack.

The federal trial in Salt Lake City will determine whether the agency must do additional searches for security camera videos.

The trial stems from a lawsuit brought by Utah attorney Jesse Trentadue. He believes a video exists showing Timothy McVeigh was not alone in detonating the bomb, and that the FBI has not adequately searched for the video.

Trentadue says his brother bore a resemblance to a police sketch released after the attack of a second suspect. He believes that explains why his brother was flown to Oklahoma after the bombing, where he died in a federal holding cell.